heater/AC doesnt work when turned to full

[Rubber_Burnin_Gal]

ive been meaning to ask this a while now but havent got round to it lol
whether i have it on heat or cold it stops working when i turn it on to FULL. its not really a problem as my air con is super cold even on 3(i usually freeze and put the window down for a bit LOL im just curious as to what it could be?

[codeunknown]

the speed switch in the fan....is the problem.... and i dont know how the speed switch is made in a vt....as i not seen it.. and there is a number of ways...
way 1 ...have different resistance coils...yes different lenghts or coil wire
way 2 ... a variable tranisiter mode ..simular to huge ballast resister with more than 1 ...and it switches in between them...
way 3 ...a complate mini coils with step down windings..
way 4... a complate little system board...

It may be possible to just replace the high speed ..if its done seperately...it may be impractical cause it could be all sealed..

it could be where the switch goes to full setting...its contact for that curcuit is damaged...

In any case you need to edge your bets ..and get a complete switch...if the car has the switch and all in one speed set there ....or the other location for speed set variable is fan assemble...the varible speed part may be easy to swap out there...or replace the fan ...blower unit..

good luck...